For example, services provided by a plurality of companies may be used by an application executed by a terminal of a user. In this case, the application logs into a target system (a communication target system) and communicates with the communication target system. When a login to the communication target system is performed, an authentication is performed using, for example, an identification (ID).    Patent Document 1: Japanese Laid-open Patent Publication No. 2014-153917    Patent Document 2: Japanese Laid-open Patent Publication No. 2013-114622    Patent Document 3: Japanese Laid-open Patent Publication No. 09-265443